Marine algae, a general term for algae in marine, are usually attached to the seabed or some solid constructions. They are simple individual plants or a long string of plants composed of basic cells. They are aquatic plants with the stalks or leaves hard to be recognized when appearing in large quantities. The organisms by the name of marine algae include numerous species. They differ greatly in shapes and belong to many biological species. What they have in common is that they live in the seawater and can synthesize organics by photosynthesis with the pigments in their bodies. The most common large marine algae are seaweeds such as green algae, red algae and brown algae. Marine algae often grow densely in an expanse in shallow water and form obvious zones on the coast where the water is less than 50 meters in depth. The marine algae growing above high-water line are often exposed to the air. On the other hand, the marine algae growing below the low-water line cannot be exposed in the air for a long time and thus cannot grow near the shore, which are, for example, the populations from the genera Fucus, Macrocystis, Nereocystis and Laminaria. They can only reproduce below 18° C. and are distributed only in cold water areas.
With the advancement of science and technology, people get increasing understandings on the application value of marine algae in industry and life. Due to extensive sources, low price and other advantages, the extracts from marine algae have become the focus in various fields. The extracts are, for instance, trehalose, algal polysaccharides, alginic acid and the inorganic salts thereof.
The trehalose is a non-reducing saccharide formed by two glucose molecules with a 1,1-glucosidic bond. It has three isomers, i.e., trehalose (α, α), isotrehalose (β, β) and neotrehalose (α, β). The trehalose commercially available in the market is typically the mixture of these three isomers, mostly trehalose (α, α). Trehalose is widely precent in many animals, plants and microorganisms in nature that can be used as food. For instance, the content of trehalose is relatively high in mushrooms, marine algae, beans, shrimps, bread, beer and yeast-fermented food that commonly appear in popelpe's daily life. The trehalose is most commonly used as the natural edible sweetener.
Also, the trehalose has a miraculous protective effect on living bodies because such a compound can form a unique protective film on the cell surface under harsh environmental conditions with a very high temperature, a very low temperature, a high osmotic pressure, a dry condition with water loss and the like. In particular, the trehalose effectively protects protein molecules from denaturation and deactivation, maintaining the life process and biological characteristics of living bodies. The extraordinary resistance to external harsh environment in many species directly relates to a large amount of trehaloses in their bodies. Such a unique functional feature enables trehalose to become an important ingredient in cosmetics maintaining cell viability and preserving moisture and also become a good activity protector for proteins, enzymes, vaccines and other biological products. Moreover, it may also function as a unique food ingredient which can prevent food degradation, preserve the fresh flavor of food and improve food quality. This feature has greatly expanded the application of this compound. Similar to trehalose, algal polysaccharides are all safe and reliable natural saccharides from marine algae.
The alginic acid is a powder of light yellow and almost odorless. It is a polysaccharide generated from linear polymerization of monosaccharide-derived uronic acidanda. Alginic acid is mainly originated from brown algae such as kelp, gulf weed, yellow tang and giant kelp. At present, alginic acid is used in the adhesive agents and disintegrating agents in the pharmaceutical field. Sodium alginate, calcium alginate and potassium alginate which are the inorganic salts of alginic acid are similar to alginic acid in nature.
It is a task for the professionals to explore more fields where the resourceful algae extracts can be applied.